In his first-ever interview, the sole Australian survivor of the Waco siege has revealed to 60 Minutes what really took place during the 51-day stand-off, and why he believes crazed cult leader David Koresh will one day return to Earth as the son of God.

Autopsy reveals drug intoxication and immersion in water led to death of Bobbi Kristina Brown

A medical examiner says Bobbi Kristina Brown's face being immersed in water, along with drug intoxication, led to her death last year.

The Fulton County Medical Examiner's office in Atlanta released a statement on Friday morning (US time) on the death as it prepares to release the full autopsy report.

The 22-year-old daughter of singers Whitney Houston and Bobby Brown was found face-down and unresponsive in a bathtub in her suburban Atlanta home January 31, 2015, and died in hospice care on July 26.

The office said it reviewed medical records, investigative files and other documents to determine how Brown likely died. The medical examiner's office said marijuana and alcohol were involved in the death, along with medications used for sedation or to treat anxiety.

A judge on Thursday granted a request filed by media organisations to unseal the autopsy.